Investigation of the characteristic structural features of the new class of peptide antibiotics to provide informtion on their structure-activity relationship is the goal of this proposal. Synthesis of Alamethicin I and II, Antiamoebins I and II, Emerimicins I, III and IV as well as the appropriate analogs of these ionophores will be carried out to provide proof of their sequences. These synthetic peptides will be characterized alone with the naturally occurring peptides using mass spectrometry, membrane-activity and antibiotic activity studies. A careful evaluation of the influence of the conformation(s) of these peptides on their pore-forming properties will be made and proposal of a model system to provide insight into the nature of the natural ion channels of nerve and other tissues.